Common venting system for heating, cooling and domestic hot water systems

ABSTRACT

A common vent application and an independent fan coil are disclosed for improved heating, cooling and water making in a building. The independent fan coil obviates the common boilers and chillers in addition to all the common heating and cooling distribution piping used in known systems. Instead, the fan coils contain all the hydronic heating components and all the components needed to provide AC without the use of common boilers and chilled water systems. The fan coils utilize common vent shaft ducting to exhaust the products of combustion generated for the independent tankless water heater. In addition, the common vent shaft may utilize a negative static pressure environment to exhaust the heat of rejection from the AC portion of the fan coil unit.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 16/229,913, filed Dec. 21, 2018, which claims the benefit of U.S. Provisional Application No. 62/708,804, filed Dec. 26, 2017 which is incorporated herein by this reference in its entirety.

COPYRIGHT NOTICE

© 2017-2018 1026970 BC Ltd., B.C., Canada. A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 37 CFR § 1.71(d).

TECHNICAL FIELD

This disclosure pertains to heating, cooling, and hot water systems primarily for installation in residential structures, and more specifically to common venting methods and apparatus for venting exhaust gases in multi-story structures.

BACKGROUND

Historically, low-rise and high-rise apartments have been heated and cooled with common boilers and common chilled water systems. The heating and cooling transfer agents (water, glycol or various refrigerants) are heated with a common boiler and chilled with a common chiller system, and then pumped into a piped common distribution system into a 4-pipe fan coil unit in each independent suite; 2 pipes supply hot water for heating and two pipes supply chilled water for AC. Since the distribution systems extend over several stories, the transfer agent is generally pumped under pressure and or gravity is used to supply the transfer agent from the roof down to the fan coil units in each suite. Since high flow rates are needed to move the transfer agent throughout the structure piping, and the individual suite fan coils require lower transfer agent flow rates to function, balancing valves are required on the supply piping to each fan coil. These systems have been notoriously difficult to balance effectively. The need remains for improvements in heating, cooling and domestic water systems in multi-story structures. Methods and apparatus disclosed herein can be used to improve operation, cost and efficiency of such system.

SUMMARY

The following is a summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.

With a common vent application and an independent fan coil system in each suite as disclosed herein the foregoing problems may be mitigated. The independent fan coil systems obviate all the common boilers and chillers in addition to all the common heating and cooling distribution piping. Instead, the fan coils contain all the hydronic heating components and all the components needed to provide AC without the use of common boilers and chilled water systems. The independent fan coil systems utilize a common vent shaft ducting to exhaust the products of combustion generated for the independent tankless water heaters. In addition, the common vent shaft may utilize a negative static pressure environment to exhaust the heat of rejection from the AC portion of the fan coil unit. In some embodiments, a common vent pipe may be installed in a vertical service shaft rather than using a dedicated common vent shaft.

The common venting system can be used to receive combustion gasses from each individual suite tankless on demand appliance on several levels after which the products of combustion vent to the atmosphere.

In an example, a new system to heat and cool structures without the use of common strata use mechanical systems and has the potential to reduce carbon emissions, greenhouse gases and allow the occupants true autonomous control over their heating and cooling systems.

In an embodiment, a system for installation in a structure comprising plural individual suites may comprise: a common vent shaft arranged to provide air flow from two or more of the suites to the exterior of the structure; and an independent fan coil system installed in one of the suites, the independent fan coil system coupled to the common vent shaft and including: a heating section to receive return air from the suite, warm the return air, and deliver the warmed return air to a plenum; connections coupling the heating section to a source of hydronic heating fluid for said warming the return air; and a cooling section to cool the return air and supply it to the plenum.

In another embodiment, an independent fan coil system comprises:

a controller arranged to receive input signals from a thermostat and generate control signals responsive, at least in part, to the input signals;

a heating section arranged to receive the return air, warm the return air, and deliver the warmed return air to a plenum responsive to control signals generated by the controller;

the heating section including a hydronic coil coupled to receive hydronic heating fluid for said warming the return air; and

a cooling section to cool return air and supply it to a plenum; and

the cooling section including a heat pump system for removing heat from the return air and or from incoming air from a separate supply air duct.

Additional aspects and advantages of this invention will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified diagram illustrating an example of a common venting system in a structure consistent with the present disclosure.

FIG. 2 illustrates in detail the fire stop devices used in FIG. 1.

FIG. 3A is a simplified diagram illustrating heating and cooling operations of an independent fan coil system;

FIG. 3B is a simplified diagram illustrating heating, cooling and water making operations in the independent fan coil system of FIG. 3A;

FIG. 3C is a simplified diagram illustrating an alternate embodiment of an independent fan coil system with an internal tankless water heater;

DETAILED DESCRIPTION

FIG. 1 is a simplified diagram illustrating an example of a common venting system application consistent with the present disclosure. In FIG. 1, a cross-sectional view is shown comprising four floors or suites in a structure such as a condominium or apartment building, although the structure may be for commercial or residential (or mixed) use. The system may be used with more (or fewer) than four floors; the drawing is merely illustrative. On each floor, a tankless on-demand water heater 101 is installed. Each water heater 101 has an exhaust vent pipe 102 for venting exhaust (combustion) gases, through a corresponding back-draft damper 103, into a common vertical shaft 105 built into the structure.

Common vertical shaft may also operate at different static pressure settings, to evacuate the heat of rejection produced from the AC in fan coil unit, see FIGS. 3A, 3B and 3C fan 121 can be located at the top of the common vent shaft 105 to create a negative static pressure. In operation, air enters into the bottom of the shaft by means of a shaft opening 123, and the pressure differential between the air leaving the shaft and the air entering the shaft creates a negative static pressure in the shaft 105. This serves to evacuate the heat rejection at a faster rate, facilitating smaller shaft sizing in the structures.

The exhaust vent pipe penetrates the wall via a fire stop 106 where it enters the shaft. Fire stops should be used consistent with local building codes. The damper 103 is arranged to prevent combustion gases from entering the suite. Inside the shaft, in an embodiment, each of the exhaust vent pipes is connected to a generally vertical, common vent pipe 104. In another embodiment, the shaft may be dedicated for exhaust gas removal without requiring a venting pipe. In another embodiment, more than one common venting pipe may be used. The common shaft may be constructed of wood, concrete, or other rigid materials. Preferably those materials are fire rated to impede the spread of fire from one floor to another.

In an embodiment, the common vent pipe 104 can be configured to operate under a positive pressure at the base of the vent, provided by means of a fan 107. Alternatively, the common vent may be configured to operate under a negative pressure, provided by means of a fan 108 at the top of the common vent where, in operation, the venturi effect draws the exhaust gases from the common vent pipe 104 to exit via a vent cap 118 on the roof to the atmosphere outside of the structure. The negative static pressure can be controlled by a static pressure sensor (not shown) to modulate the pressure inside common vent 104A. A drain 109 may be installed at the base of the common vent 104 to accommodate condensation accumulation in the common vent pipe. Preferably, for most applications, the common vent pipe 104 should also utilize an expansion joint for each exhaust vent pipe 102 to facilitate the expansion and contraction of the vent pipe 104 and negate the strain on exhaust vent pipe 102 when it connects to common vent pipe 104.

In an embodiment, the tankless on demand water heater 101 receives a supply of cold water (not shown). The water heater within each apartment supplies heated water via piping 110 to an air handler 111 and a heat exchanger 112 within the air handler 111. Warm air via duct 113 is then supplied to each individual apartment; and conversely cold air/air conditioning can be supplied to each individual apartment via a cooling coil 114 and an external condensing unit (not shown) to provide cooling fluid to the cooling coil 114. Warm air via duct 113 also provides suite ventilation. A pipe 120 supplies hot water for domestic use in each suite. FIG. 2 illustrates the fire stops 106 in FIG. 1 in detail. Suitable fire stops are commercially available.

Independent Fan Coil System—Call for Space Heating

FIG. 3A is a simplified diagram illustrating, essentially in cross section, the main components and selected operations of an independent fan coil system 300. In FIG. 3A, T-Stat controller 337 sends a call for heat signal to a programmable controller PLC 308. In response, PLC 308 energizes solenoid valve 306 which opens louver 303. Louvers 301, 302 remain closed in heating mode. PLC 308 signals fan blower motor 309 to start, air then enters the independent fan coil system through return air duct 311 and filter 319. PLC 308 then starts tankless water heater 310 and the pump 331 to supply heated heat transfer liquid to a hydronic coil 307 by means of supply and return piping 332. Blower motor 309 forces return air from the suite through coil 307 and louver 303 into plenum 313 and thence into supply air ducts 314 and into the suite for space heating.

Combustion air for the tankless water heater unit 310 enters through piping 334 which can be accessed from the common vent shaft (FIG. 1, 105) or through a vent hood and ducting in the exterior wall of the structure. Combustion gases exiting the water heater unit 310 are conveyed via piping 335 to the common vent shaft of FIG. 1 and into the exhaust ducting pipe (FIG. 1, 104) and vent to atmosphere. The shaft wall 318 corresponds in one embodiment to the wall 122 of FIG. 1. Combustion air and exhaust air piping preferably utilize firestop devices (FIG. 2, 106) to prevent fire from entering the shaft from the suite and prevent a shaft fire from entering the suite. The tankless water heater 310 will supply domestic hot water for showers and washing etc. to the suite (piping not shown) at same time as supplying the transfer liquid via pump 331 to the hydronic coil 307 for space heating. In an embodiment, should the space heating demand and the domestic demand become greater than the heating capacity of the tankless water heater 310, then PLC 308 will disable space heating demand for a selected period, for example, 30 minutes, until the domestic water requirement are satisfied.

In some embodiments, PLC 308 will monitor a static pressure sensor 338 in the supply air ducting 314 to maintain a constant positive static pressure of 0.8 to 1.2. This pressure is measured in External Static Pressure (ESP) units and refers to air pressure differential across the air handler. It refers to the total ESP; thus, in one example, supply air is 0.4 and return air is 0.4 so that ESP is the sum of both or 0.8. This feature allows for substantially smaller supply air duct, giving structural designers more freedom to conceal the supply air ducting, negating the need for unsightly and expensive drop ceilings. PLC 308 will signal blower motor 309 which preferably is a constant torque motor to speed up or slow down to maintain the preset static pressure required in the supply air ducting 314. Alternatively, PLC 308 may monitor blower rpm to maintain constant static pressure by altering rpm to meet setpoint demand.

Principles of Operation FIG. 3A Call for Space Cooling Air Conditioning

T-Stat controller 337 may send a call for cooling signal to PLC 308. In response, PLC 308 energizes solenoid valve 304 which opens a louver 301. PLC 308 also energizes solenoid 305 which opens louver 302. Louver 303 remains closed in cooling mode. PLC 308 signals fan blower motor 309 to start. Air then enters the independent fan coil system 300 through return air duct 311 and filter 319, and through louver 301, and evaporator coil 312, and through louver 302 into plenum 313 and thence into supply air ducting 314 into the structure to provide air-conditioning.

PLC 308 starts blower motor 315, air enters thru air supply duct 316 and air filter 320, air then flows thru condenser coil 317, the heat of rejection passes thru fire protected wall 318 and then into the common vent shaft (FIG. 1) 105 and vents to atmosphere thru the roof. PLC 308 then starts compressor 321 land refrigerant flows thru refrigerant lines 334 and 349 to complete the heat pump configuration. Compressor 321 preferably is configured in the air stream provided by blower motor 309 to provide additional cooling for the compressor. Compressor 321 can utilize R134a, 410A or a varied to refrigerants for the heat pump circuit; rotary compressors are preferable. PLC 308 will allow the tankless water heater to continue to supply domestic hot water during this mode of operation. Condensate produced by the evaporator coil 312 will be piped to drain 322.

Referring now to FIG. 3B, PLC 308 also starts blower motor 315. Blower 315 draws air into the system through air supply duct 316 and air filter 320. That supply air then flows through condenser coil 317, and the heat of rejection passes through fire protected wall 318 and into the common vent shaft and vents to atmosphere through the roof of the structure (see FIG. 1). PLC 308 then starts compressor 321 and refrigerant flows through refrigerant lines 334 and 349 to complete the heat pump configuration. Compressor 321 is configured in the air stream provided by blower motor 315 to provide additional cooling for the compressor. Compressor 321 can utilize R134a, 410A or various other refrigerants for the heat pump circuit. Rotary compressors are preferable. PLC 308 will allow a tankless water heater to continue to supply domestic hot water during this mode of operation. Condensate produced by the evaporator coil 312 should be piped to drain 322.

Principles of Operation FIG. 3B Heating, Cooling and Water Making

Heating operation is as described with regard to FIG. 3A for space heating.

Cooling Operation & Water Making

Referring again to FIG. 3B, in this operation, PLC 308 receives a signal from water storage tank 326 that drinking water is required. Responsive to control signals from the PLC, louvers 303 and 301 remain closed, solenoid 305 opens louver 302, solenoid 339 opens louver 338, and solenoid 329 operates louver 328 to remain closed. PLC 308 starts blower motor 315, air enters through air supply duct 316 and air filter 320, air then flows through the condenser coil 317, the heat of rejection passes through fire damper 318 and then into the common vent shaft (FIG. 1) 105 and vents to atmosphere through the roof. PLC 308 then starts a compressor 321, and (third) blower fan 323, and refrigerant flows through refrigerant lines 334 & 349 to complete the heat pump configuration. Moist air then enters the independent fan coil system 300 through air duct 324, filter 325 and louver 338. It further moves through evaporator coil 312, through louver 302 into plenum 313, and from the plenum into supply air ducting 314 into the suite or apartment to provide air-conditioning. Water produced by the evaporator coil 312 is piped to water storage thank 326 by drain 322. The evaporator coil 312 should be made of pure copper or coated with a nontoxic coating to produce potable water.

When the water storage tank 326 is full, it sends a signal (not shown; may be wired or wireless) to PLC 308 which, in response, turns off the water making. If T-Stat 337 is signaling for AC during this mode of operation, the controller 308 sends control signals to solenoid 329 so that louver 328 remains closed, and to solenoid 333 so that louver 327 remains open, and AC is provided to the suite while water for drinking is being produced. When T-Stat 337 is not sending a signal to PLC 308 for AC, once again responsive to control signals from the controller (PLC 308), louver 327 closes, louver 328 opens and excess cold air is vented to the common vent shaft through ducting 330. If T-Stat 337 calls for space heating during water making mode, then PLC 308 overrides water making until space heating demand is satisfied, louver 328 is closed and louver 327 remains open.

Principles of Operation FIG. 3C Heating/AC/Domestic Water/Water Making

In this alternative configuration, an independent fan coil system 300 has an internal tankless water heater 310. Here, the tankless water heater 310, the associated pump 331 and supply and return piping 332 are housed in the independent fan coil system. Further, the evaporator 312 is configured in front of hydronic heating coil 307, solenoids 305, 306 and louvers 302, 303 are not required. The compressor 321 is configured to receive air flow from blower motor 315.

FIG. 3C Heating Mode

T-Stat controller 337 sends a call for heat signal to PLC 308, PLC 308 signals fan blower motor 309 to start, air then enters the independent fan coil system through return air duct 311 and through filter 319. PLC then starts the tankless water heater 310 and the pump 331 to supply the heat transfer liquid to hydronic coil 307 by means of supply and return piping 332. Blower motor 309 forces return air from the suite through hydronic coil 307 and louver 303 into plenum 313 and into supply air duct 314 and into the suite for space heating.

Combustion air for the tankless unit 310 enters through piping 335 which can be accessed from the common vent shaft (FIG. 1, 105) or through a vent hood and ducting in the exterior wall of the structure. Combustion gas 335 enters the common vent shaft and into the exhaust ducting (FIG. 1, 104) and vents to atmosphere. Combustion air and exhaust air 335 utilize firestop devices (FIG. 2, 206 for example) to prevent fire from entering the shaft from the suite of a shaft fire from entering the suite. The tankless water heater 310 will supply domestic hot water for showers and washing etc. to the suite at the same time as supplying the transfer liquid to the hydronic coil 307 for space heating. Should the space heating demand and the domestic demand become greater than the heating capacity of the tankless water heater 310, then PLC 308 will disable heating demand for 30 minutes, for example, until the domestic water requirements are satisfied. PLC 308 may monitor a static pressure sensor (338 in FIG. 3B) in the supply air ducting 314 to maintain a constant positive static pressure as described. PLC 308 will signal blower motor 309, which preferably is a constant torque motor, to speed up or slow down based on a pressure indication from the pressure sensor 338 so as to maintain the preset static pressure required in the supply air ducting 314. Conversely, PLC 308 may monitor blower rpm to maintain constant static pressure by altering rpm to meet setpoint demand.

FIG. 3C Cooling Mode

T-Stat controller 337 send a call for cooling signal to PLC 308. PLC 308 signals fan blower motor 309 to start, air then enters the independent fan coil system through return air duct 311 and through filter 319 into plenum 313 and thence via supply air ducting 314 into the structure to provide air-conditioning. PLC 308 starts blower motor 315, air enters through air supply duct 316 and air filter 320, air then flows through condenser coil 317, the heat of rejection passes through fire damper 318 and then into the common vent shaft (FIG. 1) 105 and vents to atmosphere through the roof. PLC 308 then starts compressor 321 and refrigerant flows through refrigerant lines 334 &349 to complete the heat pump configuration. Compressor 321 is configured in the air stream provided by blower motor 315 to provide additional cooling for the compressor. Compressor 321 can utilize, for example, R134a, 410A or a varied to refrigerants for the heat pump circuit; rotary compressors are preferable. PLC 308 will allow tankless water heater to continue to supply domestic hot water during this mode of operation. Condensate produced by the evaporator coil 312 may be piped to drain 322 to water storage tank 326 (FIG. 3B).

FIG. 3C Water Making Mode

PLC 308 receives a signal from water storage tank 326 that drinking water is required. PLC 308 starts blower motor 315, air enters through air supply duct 316 and air filter 320, air then flows through condenser coil 317, the heat of rejection passes through fire damper 318 and then into the common vent shaft (FIG. 1) 105 and vents to atmosphere through the roof. PLC 308 then starts compressor 321, blower fan 323 (FIG. 3B) and refrigerant flows through refrigerant lines 334 and 349 to complete the heat pump configuration. Moist air enters the independent fan coil system through air duct 311 and filter 319. It further flows through evaporator coil 312, into plenum 313 and via supply air ducting 314 into the structure to provide air-conditioning. Water produced by the evaporator coil 312 is piped to water storage thank 326 by drain 322. When water storage tank is full it sends a signal to PLC 308 which turns off the fan coil. If T Stat 337 is signaling for AC during this mode of operation, louver 328 remains closed under control of solenoid 329, louver 327 remains open, and AC is provided to the suite while water for drinking is being produced.

When T-Stat 337 is not sending a signal to PLC 308 for AC then louver 327 closes louver 328 opens and excess cold air is vented to the common vent shaft through ducting 330. If T-Stat 337 calls for space heating during water making mode then PLC 308 overrides water making until space heating demand is satisfied, louver 328 is closed and louver 327 remains open.

In various configurations, electric tankless water heaters may be used instead of gas fired heaters. Those configurations obviate the need to supply and remove combustion gases. A common shaft may still be used to remove excess heat of rejection.

It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the following claims.

Most of the equipment discussed above comprises hardware and associated software. For example, the typical electronic device is likely to include one or more processors and software executable on those processors to carry out the operations described. Above, the PLC 308 may be a software-driven controller. We use the term software herein in its commonly understood sense to refer to programs or routines (subroutines, objects, plug-ins, etc.), as well as data, usable by a machine or processor. As is well known, computer programs generally comprise instructions that are stored in machine-readable or computer-readable storage media. Some embodiments of the present invention may include executable programs or instructions that are stored in machine-readable or computer-readable storage media, such as a digital memory. We do not imply that a “computer” in the conventional sense is required in any particular embodiment. For example, various processors, embedded or otherwise, may be used in equipment such as the components described herein.

Having described and illustrated the principles of the invention in a preferred embodiment thereof, it should be apparent that the invention may be modified in arrangement and detail without departing from such principles. We claim all modifications and variations coming within the spirit and scope of the following claims. 

What is claimed is:
 1. A common venting system for a structure housing multiple suites, the venting system comprising: a rigid common venting pipe having a plurality of exhaust gas inlet ports, each exhaust gas inlet port arranged to receive exhaust gases generated by separate individual corresponding water heater units; an exit port coupled to the venting pipe and arranged to exhaust gases from the venting pipe to the atmosphere; and a pressure means coupled to the common venting pipe for maintaining a preset static pressure in the common venting pipe to draw the exhaust gases, in operation, through the common venting pipe toward the exit port.
 2. The venting system according to claim 1, wherein the pressure means comprises a fan arranged near a bottom end of the common venting pipe to supply forced air into the common venting pipe to maintain positive static pressure in the common venting pipe to move air, in operation, upward through the common venting pipe toward the exit port.
 3. The venting system according to claim 1, wherein the pressure means comprises a first fan arranged near a top end of the common venting pipe to maintain negative static pressure in the common venting pipe to move the exhaust gases, in operation, toward the exit port; and further comprising a common shaft in which the common venting pipe is installed, the common shaft having an air inlet to supply air into the common shaft; and an exhaust fan to exhaust air from the common shaft to the atmosphere.
 4. The venting system according to claim 1, wherein the common venting pipe is formed of a rigid plastic material and is mountable inside a hollow vertical shaft configured to extend through a structure to a roof of the structure.
 5. The venting system of claim 1, further comprising a plurality of independent fan coil system connected one each in fluid communication with one each of the plurality of exhaust gas inlet ports, wherein each of the plurality of independent fan coil systems comprise: a controller arranged to receive input signals from a thermostat and generate control signals responsive to the input signals; a heating section responsive to control signals generated by the controller and comprising a hydronic coil coupled to receive hydronic heating fluid to warm air and supply the warm air to a plenum; and a cooling section responsive to control signals generated by the controller and comprising a heat pump system to cool air and supply the cool air to the plenum.
 6. The venting system of claim 5, wherein each cooling section comprises: an evaporator coil; a condenser coil; refrigerant lines operatively interconnecting the evaporator coil and the condenser coil; a compressor coupled to the refrigerant lines to compress refrigerant; a blower fan to move air over the evaporator coil for cooling and water making; and a secondary air duct to receive moist air via a filter and a louver; whereby, in operation, moist outside air from the secondary air duct flows across the evaporator coil by means of the blower fan to make water for delivery to a water storage tank.
 7. The venting system of claim 6, wherein the controller is programmed to: receive a signal from a water storage tank indicating that drinking water is required; responsive to the drinking water signal, generate control signals to: close off air flow through the heating section, enable air flow from the secondary air duct into the cooling section, enable air flow from the cooling section into the plenum, start the compressor so that refrigerant flows through the refrigerant lines to operate the heat pump system; and start the blower fan motor so that air enters through the secondary air duct and flows through the condenser coil, and into a common vent shaft so that the heat of rejection of the heat pump system passes into the common vent shaft and vents to atmosphere; whereby, in operation, moist air enters the independent fan coil system through the secondary air duct, and moves through the evaporator coil, and into the plenum, and from the plenum via supply air ducting into a suite of the structure to provide air-conditioning, and water produced by the evaporator coil is supplied to the water storage tank.
 8. The venting system of claim 6, wherein the controller is programmed to: receive a water storage tank full signal; responsive to the water storage tank full signal, turn off the fan coil system, qualified by: receiving a call for AC signal from the thermostat during this mode of operation; and responsive to the call for AC signal, generate control signals so that AC is provided to the suite while water for drinking is being produced.
 9. The venting system of claim 6, wherein the controller is programmed to: when the thermostat is not sending a signal to the controller for AC, generate control signals so that excess cold air is vented to the common vent shaft.
 10. The venting system of claim 6, wherein the controller is programmed to: responsive to receiving a call for space heating during a water making mode of operation, pausing water making until the space heating demand is satisfied.
 11. The venting system of claim 5, further comprising a plurality of water heaters one each connected in fluid communication with the hydronic coil of one of each of the plurality of independent fan coil systems.
 12. The venting system of claim 11, wherein each of the plurality of water heaters are a tankless water heater. 